Back in September, we brought you news of Peugeot’s incredible 3D printed Fractal concept car, a convertible four-seater packing some unusual punches. That vehicle, which debuted at the Frankfurt Auto Show, boasted impressive road specs, but it was one particular design feature that got everyone talking—or rather, listening.

The Fractal, a 12.5 x 5.8 ft roadster that can go from 0-62mph in 6.8 seconds, was designed to be an audiophile’s dream car. Everything about the car’s design had been adjusted to minimize external sound and emphasize the vehicle’s futuristic, 13 speaker, SubPac bass-equipped sound system. How did Peugeot plan to achieve this? Through precise, 3D printed acoustic surfaces, of course. “The Fractal name is a reference to the 3D print models shaped as anechoic chambers and repeating patterns,” said Jérôme Micheron, Strategic Director at Peugeot.

The interior surfaces of the Fractal, 82 percent of which were 3D printed, were shaped to reduce echo and precisely sculpt the sounds heard by the driver, making the driving experience a mode of transport and sound installation in equal measure.

Peugeot’s melodious 3D printed super-mini danced to its own beat at the Frankfurt Auto Show, turning more than a few heads. However, at that point in time, we didn’t know who was responsible for the impressive 3D printed parts of the car. Had Peugeot developed its own 3D printer and carried out the work in-house, or had a 3D printing expert been called in to help?

Perhaps Peugeot’s own 3D printer malfunctioned at the last minute, or perhaps the French company simply wanted to keep the spotlight on its own achievements, because it has since emerged that 3D printing giant Materialise produced the additively manufactured elements of the Fractal after the auto manufacturer called for assistance at short notice.

“We were working on a very tight deadline with this project,” explained Matthias Hossann, Head of Concept Cars & Advanced Design at Peugeot. “That’s why we thought of Materialise first, because we knew that the large printing capacity here would give us a good shot at making the deadline despite the short notice.”

Peugeot had already given the basic details of the 3D printed components of the Fractal, as well as other design features such as bass speakers built into seats and a synthetic engine sound composed by Brazilian musician and producer Amon Tobin. Materialise has now gone into greater depth about the 3D printing process behind the Fractal: The car’s “anechoic sound chamber” was designed with a high level of geometric complexity—impossible to produce using injection molding, but a piece of cake for the laser sintering 3D printers at Materialise.

The surface designs were so complex, however, that the design files had to be sliced into smaller pieces using Materialise’s Build Processor software prior to 3D printing. Its Streamics software was then used to monitor workflow. All 3D printed parts were laser sintered in polyamide, a white material, which was then flocked to improve weather resistance and add a velvety texture to the parts.

“It wasn’t just that the lead time for this project was short, but to make things even more challenging, we had to deliver a large number of parts at the same time,” said Gregory Gesquiere at Materialise France, who coordinated the project. “Our production team did an amazing job with finishing and flocking all the parts in time, to the customer’s satisfaction.”

Peugeot’s experimentation with 3D printed internal surfaces could soon be adopted by other car manufacturers, with optimized sound systems becoming a more and more important element of luxury cars. Good news for Materialse; great news for audiophiles.